The present invention relates to a warning system for multi-lane roadways, particularly divided highways and limited access highways having entrance and exit ramps. Such highways present a danger to distracted or inattentive drivers who enter a divided highway on the wrong side, perhaps by mistaking an exit ramp for an entrance ramp or an entrance ramp for an exit ramp. Prior art solutions to this problem involve the posting of signs such as "WRONG WAY", "ONE WAY", or "GO BACK". Signs, however, are of little use to inattentive drivers who might not see them. Furthermore, signs can be rendered ineffective by darkness, rain or fog and can be completely removed or destroyed by collisions with passing vehicles. If a motorist does not see the sign or if the sign is missing, the motorist will proceed onto the multi-lane highway in the wrong direction with possibly tragic results. Warning signs are therefore an inadequate solution to the problem.
Also known in the prior art of roadway warning systems is a series of raised pavement strips known as rumble strips. Rumble strips, however, typically extend across a series of lanes and have never been used as a means for warning motorists driving the wrong way on entrance or exit ramps.